Abstracts of Papers Read Before Branches.
Very Low Temperatures—Their Attainment and Uses.
Temperatures lower than any existing naturally in the universe have been attained in scientific laboratories. While theoretically there is no upper limit to the temperatures which can be achieved, a simple experiment reveals the lower limit, known as the “absolute zero.”
Temperature and Pressure Measurement.
The measurement of low temperatures presents certain difficulties which will be appreciated when it is realised that mercury becomes solid at the comparatively high temperature of 234·3° Abs. Certain other liquids with lower freezing points can be used for temperatures down to that of liquid air, but gas thermometers are used for all but the very lowest temperatures. These are usually of the constant-volume type in which the change in pressure of the fixed volume of gas is a measure of the change in temperature. Hydrogen and helium are the gases most commonly used. The fact that the electrical resistance of a wire is reduced as its temperature is lowered is made use of in temperature measurement, and this method is very convenient for low temperatures. Platinum is most commonly used down to about 20° Abs.
Liquefaction and Solidification of Gases.
Hydrogen liquefiers are to-day installed in a number of specialised laboratories. Improvements in design have, of course, been made, but the principle of operation remains the same as that used by Dewar. Pre-cooling, in order to reduce the temperature of the gas below its inversion point, is done usually by liquid air or liquid nitrogen and the compressed gas after passing through a heat exchanger, is expanded through a valve where liquefaction takes place due to the Joule-Thomson Effect.
Solid Carbon Dioxide.
Solid carbon dioxide surrounds itself with a layer of vapour having a good insulation effect, and this combined with its high density (1·56) and high latent heat (87·2 cals. per gram), ensures that the loss due to evaporation is very small. The ordinary commercial 25lb. blocks can be preserved in suitably insulated containers for several days without appreciable loss. For this reason it can be transported economically for long distances.
One of the most valuable discoveries of recent years is the fact that foodstuffs may be preserved for longer periods than formerly when they are surrounded by a carefully controlled atmosphere of carbon dioxide.
Industrial and Scientific Applications.
In addition to the manufacture of solid carbon dioxide, the principal industrial applications of low temperature technique are the separation of oxygen, nitrogen and the rare gases from atmospheric air.
Petroleum and Some of Its Products.
Engine performance in aircraft is largely governed by the characteristics of the fuel used. N-paraffin octane has practically no value as an anti-knock fuel, but the isomer iso-octane has an octane number of 100 and is used as one of the reference fuels in the C.F.R. engine.
The higher the knock rating of a fuel, the higher the compression ratio that may be incorporated in the design of the engine using the fuel and the greater the increase in power output that can be obtained. There is no point in using a very high knock rating fuel in an engine that was not designed for it.
In the last 10 years aviation spirits have increased in anti-knock rating by 25 octane numbers, and in a similar period the motor spirits on the New Zealand market have increased by 10 numbers. The earliest way of increasing anti-knock value was by the addition of benzol and later by lead tetra ethyl. Modern practice tends towards refining methods for increasing knock ratings of fuel by cracking processes. As a result of these cracking processes, large quantities of refinery gases are obtained as by-products, and these are polymerised catalytically. About 40,000,000 gallons of Polymer gasoline are available from U.S.A. from this source.
Numerous petroleum thinners with special boiling range characteristics are produced and marketed with almost any chemical composition or boiling range desired within reasonable limits. They may be used either as true solvents or as in the case of the newer synthetic finishes, rather as diluents or extenders to the true solvents of the basic materials. They reduce the viscosity and consistency of the finish, aiding proper application and assisting levelling in the case of paints.
The production of alcohols and ketones from refinery gases on a commercial scale is a development of recent years which has made many chemical solvents available to industry.
By the use of solvent extraction processes from the acid sludges from the refineries are produced naphthenic acids, which are the base of some of the most effective driers used in the production of paints and varnishes. Glycerine has been produced from petroleum by-products on the plant scale by methods that were not envisaged in chemical text books of 10 years ago. It would appear that the ever-increasing tempo of the petroleum industry will by synthesis become an important producer of many chemicals required in other industries.
Two Fungus Parasites of Ryegrass.
J. C. Neill, Chief Mycologist, Plant Diseases Division,
Department of Scientific and Industrial Research.
1. The Causal Fungus of Blind-seed Disease.
It has been noted for many years past in New Zealand and elsewhere that, at times, apparently normal healthy ryegrass seed might germinate very poorly under test. Wet weather between blossoming and harvest was associated with such occurrences, generally ascribed to defective pollination. The introduction in 1930 of a certification system for crops of an approved strain of ryegrass led to this low-germination trouble assuming national importance. The Hawke's Bay strain, on which certification was based, became particularly susceptible to the trouble when grown in the Manawatu or Southland.
Work in New Zealand has shown that the trouble is a disease caused by a specific fungus. It was given the name of Blind-seed Disease. The full life-history of the fungus has been worked out and is briefly as follows:
The non-germinating “blind-seeds” carry a mass of fungus tissue in the endosperm and are the carry-over phase of the disease. After lying some 10 months at the soil surface, they produce spore-bearing apothecia coincident with the flowering period of the ryegrass. The apothecium discharges its spores into the air, where they are carried to open blossoms, germinate, and attack the developing seed. At this stage a syrupy exudate is produced containing multitudes of conidia, and this in wet weather is washed and conveyed by contact to other flowers to infect further seeds. In dry weather little exudate is produced and there is little spread of the disease. The disease should be controllable, even in wet years, by avoiding the fall of diseased seeds in the summer preceding that of harvest, that is, by preventing all seeding by hard grazing and mowing. For new sowings the same end can be achieved by sowing high test or two-year-old seed, since the fungus does not survive eighteen months' storage.
2. The Ryegrass Endophyte.
During a co-operative investigation into the cause of the stock malady known as “Facial Eczema” it was found that leaves of ryegrass from affected pastures were permeated by fungus hyphae that showed no outward indication of their presence. Further work showed that this phenomenon was general in the “certification” type of Hawke's Bay perennial ryegrass pastures, whether Facial Eczema had occurred or not.
The fungus was generally absent from the Southland and Manawatu types of “false perennial” and entirely absent in Italian ryegrass.
It was found that the fungus was carried in the seed as a thin weft of hyphae overlying the aleurone layer, that, as the seed germinated, it penetrated the growing point and tiller bases and kept pace with the developing leaves, stems, flower organs, and finally the seed. The hyphae penetrated between the cell walls and through the intercellular spaces without any apparent effect on the adjacent plant cells. No fructifications have been found.
The fungus is not an obligate parasite, since it has been obtained in artificial culture and it appears to have little or no adverse effect on the host plant. Mycologically it appears to be closely allied to the Blind-seed fungus, but with a very different etiology. It resembles and may be identical with the known endophyte of darnel—an annual “weed” ryegrass to which has been ascribed poisonous properties since Biblical times. It was found that infected seed kept for two years produced plants free from the fungus, and this has allowed the laying down of pastures of the same strain of ryegrass with and without the endophyte for stock feeding trials.
Forest Remains on Present Tussock Grassland.
F. W. Hilgendorf.
The forest remains described by Speight (Trans. R.S.N.Z., Vol. 49, p. 361) are also to be found in a new pit across the road. Here they rest on or in a layer of silt at least five feet thick. Similar remains are found near Prebbleton, where the Southbridge highway crosses “The River Bed.” The stumps are nearly all upright, as if grown in situ. There are six on a quarter of an acre. They are regularly disposed as if in situ. They are covered by about 12 feet of shingle as those at Sockburn are, and are all on one level. No timber apparently in situ has been found in the pits at Islington.
At a gravel pit at Cashmere there are hundreds of logs of several kinds of timber lying flat as if heaped up by flood waters.
On many of the flat-topped mountains of Central Otago there are bogs of sedges and sphagnum. On the southern end of the Lammerlaw Range, near Upper Waipori, at an elevation of 2000 to 3000 feet, some of these bogs have been partially drained by gold sluicing or other operations. Such bogs sink in level and leave round their edges deposits of timber that has been buried in the bog. The biggest pieces are about 6 feet long and 4 inches through. They look like the remains of a heavy scrub. Only heart wood is left. It is very resinous, lights with a match, and burns with a smoky flame.
In the same locality are thousands of acres where hillocks and hollows occur every ten or twenty yards. The hollows are about three feet deep, oval, about 12 feet by 8 feet. The hillocks are of corresponding size. In the hillocks are sometimes ashes, sometimes powdery dust. They are doubtless caused by the blowing over of forest trees. No trees and hardly any scrub now occur within ten miles of the position described.
The lecturer's father used to narrate that when he first visited the Dunstan goldfields in the early sixties the tussocks (probably snow-grass) were so high that one could lose a bullock among them. Now the common tussock is Poa maniatoto, which grows about one inch high.
In the discussion following the address, Mr. G. Stokell and Mr. E. F. Stead questioned whether the stumps at Prebbleton were in situ. Mr. Stokell said that not all the stumps were upright, but some were slanting, as if deposited by flood water; that one at least of them was a beech and so might have been carried down by floods
from the mountains, and that the roots of one of them were embedded in pure shingle. Mr. C. E. Foweraker, however, said that in Westland totara trees were to be found growing in pure shingle.
Mr. Stead said that a stump similar to those at Prebbleton was a few years ago carried down the Rakaia River and came ashore near its mouth. In the course of a couple of years it was gradually carried out to sea by successive floods, and every time it changed position it came to rest right side up. Furthermore, in 1916 and 1917 numerous stumps cut from forests or plantations had floated down on to the shores of Wairarapa Lake. They had all come to rest right side up. Tangled deposits of timber similar to that described at Cashmere also occurred under water at “The Timber Yard” on the shore of Lake Ellesmere.
Ranunculus paucifolius T. Kirk.
In January, 1940, at Castle Hill, the following particulars were noted regarding the state of Ranunculus paucifolius:
|Plants having 1 leaf||1|
|" " 2 leaves||25|
|" " 3 leaves||20|
|" " 4 leaves||12|
|" " 5 leaves||6|
|" " 6 leaves||5|
|" " 7 leaves||6|
|Total number of plants seen||75|
Actual total number of plants probably does not exceed 100.
Average number of leaves to each plant, three and a-half.
Number of specimens severely mutilated by animals, 15.
Number of fruiting specimens, 3.
Undoubtedly the present greatest menace to the plants lies in the danger of their being trodden on by cattle and sheep.
Unless a strong fence is put ronnd the area of three and a-half acres which covers the field of its distribution, this interesting species which for ages has succeeded in maintaining itself within the narrow confines of its present rock-encircled home, will continue gradually to perish.
Cost of materials for the fence is estimated at £60.
Studies in Hebe: II. The Significance of Male Sterility in the Genetic System.
O. H. Frankel.
1. Male sterility with female fertility has been observed in nature in eight forms of the genus Hebe, comprising five species and one species hybrid.
2. Degeneration occurs rapidly and with regularity, either in pachytene or in the course of pollen development, at a stage which is characteristic for each form.
3. In H. townsoni male sterility is associated with a timing disturbance which causes a chimerical arrangement of division stages within loculi, and also with a frequent failure of pairing of one bivalent. A causal relationship cannot be ascertained. The three phenomena may indicate a major physiological disturbance.
4. Male sterility has mainly been ascertained under experimental conditions, especially after induced self-fertilisation. Under conditions of relative isolation, which favours its occurrence, male sterility serves as a mechanism for reducing self-fertilisation.
5. In gynodiœcious species, the production of “female” plants may often, originally, be determined by single genes for pollen sterility.
Published in Journal of Genetics, Vol. XL, Nos. 1 and 2, pp. 171–184, May, 1940.
Description of a New Intestinal Protozoan from a Gecko.
Trichomonas n.sp. was described from the rectum of Hoplodactylus sp. collected on the Cass River bed. Its characteristic features were given and a comparison made with other Triehomonads from Reptilia.
The Early Development and Metamorphosis of a Brachiopod.
(An Addition to the Life History of Terebratella inconspicua.)
The unfertilised and the fertilised egg were described. Development was followed through segmentation of the egg, gastrulation, the transformation of the gastrula into the free-swimming larva, the attachment of the larva to the substratum, and the metamorphosis of the newly attached larva to form the bivalved young brachiopod. Only the external features of this development were described and figured, the internal changes being left for later consideration.
Observations on Huberia striata Smith and Discothyrea antarctica Emery.
W. E. Moore.
H. striata, an abundant ant in uncultivated areas, lives in populous but un-coördinated communities extending over an area of hundreds of square yards, and does not fight with strange ants of its own species. New colonies are normally formed by branch nests.
The little Discothyrea antarctica lives as a tolerated inquiline in nests of this species. In a colony under observation, the Discothyrea spent most of their time in the Huberia brood nest, and though sometimes threatened, were never injured.
The Ant Fauna of Swamps in the Canterbury Mountains.
W. E. Moore.
The larger patches of Sphagnum in swamps at Lake Coleridge, Cass, and Arthurs Pass are colonised by two species of ant, Monomorium nitidum and M. suteri, the latter being apparently rare elsewhere. Colonies are abundant and populous, and contain coccids.
A Revision of the Genus Retropinna.
In the press, Rec. Cant. Mus., Vol. 4, No. 6, 1941.
The Retropinnid smelts are divided into two groups by the form of the maxillary and premaxillary, the genotypic group being further divided into two sub-groups by the size of the vomerine teeth. Three new New Zealand and one new Australian species are described, Hector's species osmeroides is reinstated, and several forms of questionable specific distinctness are noted. An extraordinary range in the number of vertebrae is revealed, and this is briefly considered in relation to the distributional range.
Some Aspects of Fishery Research in Canada.
L. R. Richardson.
The Canadian fishing industry has been a prominent factor in the economic framework of the country for many years. During the past few years, fish, shellfish, and lobsters taken from Canadian waters have amounted to a value of eight to twelve million pounds per annum, with an export value of nearly two-thirds of that total. The Canadian Fisheries Board, formerly the Biological Board, was originated to survey and guard the usage of the natural resources on which this industry has developed. After thirty years, the Board now controls six main research stations in the main centres of the industry, and many smaller subsidiary stations established for the study of local aspects of major problems.
Decline in the populations of important species has called for energetic, scientific study. Improvement in the technique of lobster canning and the rapid expansion of the industry placed a heavy strain on the existing populations and threatened a major decline in the returns from the industry. This has been countered by local readjustments in the legal size limits and the period of fishing so that the most economical size of lobster is taken and canning returns have been maintained with smaller catches than before.
The problem of the oyster industry of the east coast contrasted markedly with the above situation. An epidemic wiped out the population some thirty years ago. The introduction of oyster-farming with many innovations and the development of a strain of oysters immune to the disease is rapidly returning the industry to its former status. An important improvement has been the reduction of the time for the production of a marketable oyster from seven to four years.
The decline of the east coast salmon fishery has been slow but extensive, and is a problem still under study. Present indications suggest that the problem is largely one of the fresh-waters, and research is being actively undertaken into the means of controlled development of natural spawning and hatchery waters.
The work of the Fisheries Board has been directed to the needs of the industry and is contributing increasingly to the maintenance of a valuable Canadian industry.
The History of the Moa.
This paper gave an account of a revision of the Dinornithiformes based on an examination of nearly all the type material both in New Zealand and abroad and on a considerable number of skeletons of individual birds gathered by Auckland Museum collecting expeditions during the past ten years. A new basis for classification was introduced and conclusions drawn from it as to the development and distribution of species. The phylogeny of the group was also discussed. The paper concluded with a statement of the evidence bearing on the question of the period of survival of the moa.
The Rebirth of a Race.
Some Observations on the Recent Maori Census.
In 1859 F. D. Fenton calculated that from the rate of decrease of the Maori race, the population in 1942 would be 15,343, whereas the recent census gives the population in 1936 as 82,326. In the five years 1921–1926, the pakeha and Maori increased at approximately the same rate, the figures being—European 10·69; Maori 11·73.
The next census revealed a most interesting position, as for the 10 years 1926–1936, the European rate had increased to merely 10·93, including immigration, whereas the Maori population, by natural increase only, had increased by 29·30 per cent.
A decline in the European birthrate seems inevitable, but there are many factors operating to cause the Maori rate of increase to become steadily greater. The Maori population is predominantly youthful as compared with the European population, which is predominantly adult. The non-adult Maori population is 56·59 per cent. compared with 36·16 per cent. for the European.
The drift of Maori population to urban areas is shown by an increase of 50·63 per cent. in the 10 years from 1926–1936.
Attention must be given to the figures provided by the reports on vital statistics and public health. The Maori birthrate in 1939 was 46·64 per 1000, while the European birthrate in the same year was 17·29 per 1000. The Maori death rate in 1939 was 18·29 per 1000 as against the European death rate of 9·08 per 1000. In addition, infant mortality is high with the Maori, and yet the survival rate of the Maoris is almost three times that of the Europeans.
The occupational destiny of the Maori is the crux of the problem, and herein lies the challenge of the Maori census figures. Only a small proportion of the younger Maoris receive adequate training. Too many are dependent upon seasonal demands for casual labour. If the rapidly growing Maori population is to be worthily absorbed into the national life of this Dominion, a wider training must be given in specialised activities to enable the Maori to stand equally alongside his pakeha brother or sister in the economic life of the community.
Science Teaching in New Zealand.
The June meeting of the Wellington Branch of the Royal Society of New Zealand took the form of a symposium on the subject of Science teaching in New Zealand.
The discussion indicated a marked dissatisfaction with the results of Science teaching, particularly in the post-primary schools. The opinion was expressed that to the defective teaching of Science was due the lack of science sense in the community.
An outstanding defect of Science teaching in the post-primary schools is that the course is usually designed for the relatively very small number of scholars proceeding to the university to study Science.
The Science taught in the schools has therefore little relation to the present and future needs of the average pupil.
Science is not given sufficient attention in post-primary schools, as is indicated by the fact that not more than three and a-half hours per week are given to it. An inferior position is given in the Public Service Entrance examination, where Science is allotted 200 marks and Latin 400, and the same relative marking is given in the University Scholarship examinations.
The Council of the Wellington Branch considers that the following suggestions which arose out of the discussion should be given serious consideration by the Government:—
That the subject of Science in post-primary schools should be so taught as to meet the needs of those who will receive no further formal teaching of Science.
That the time given to Science teaching be increased to at least eight hours per week.
That more emphasis be given to Science in examination programmes and that Science be made at least equivalent to Mathematics or Latin.
That the scope of Science subjects in post-primary schools be widened so as to include the biological sciences, and that their treatment should be brought into close touch with the affairs of daily life.
That steps be taken urgently to establish a distinct system of training for post-primary teachers and especially for teachers of Science in these schools.